Corrosion protection system for non-immersed equipment

ABSTRACT

An ionic transport material is disposed relative to a substrate and configured to establish an ionic connection between the substrate and a replaceable sacrificial anode. The replaceable sacrificial anode is electrically connected to the substrate and is provided to inhibit corrosion of the substrate.

FIELD OF THE INVENTION

The invention relates to inhibiting corrosion in substrates (e.g.,metals, elements, equipment, structures, and vehicles, aircraft, cars,trucks, etc.).

BACKGROUND

Corrosion protection of substrates (e.g., structures, aircraft, cars,trucks, metal parts of equipment, etc.) from moisture in air istypically accomplished by coating such substrates with a protectivecoating using specialized materials (e.g., epoxies, paints, andurethanes). However, such coatings are known to be prone toenvironmental damage and, once damaged, can leave the underlying metalsubstrate susceptible to corrosion. Although continued protection withsuch coatings can be achieved by maintenance and reapplication of thecoating, the reapplication process can be costly since it often involvesremoval of an equipment from service, complete removal of old protectionlayers, and/or application of a new protection layer

Sacrificial anodes have been used in marine applications to protectcorrosion of metal hulls and equipment that are immersed in water. Insuch applications, the water in which the parts are immersed functionsas an ionic transport medium that facilitates electrochemical connectionbetween the sacrificial anode and surfaces to be protected. However,such sacrificial anodes are not completely effective since, significantcorrosion can occur in regions, commonly referred to as “splash zones,”where water is intermittently splashed on the surface but a consistentionic connection cannot be established with the sacrificial anode toprevent corrosion of the surface.

SUMMARY

Since the ionic transport medium established between the sacrificialanode and the substrate in water cannot be established in air,sacrificial anodes cannot be as easily used to protect substrates fromcorrosion in air. Although techniques involving dispersing smallparticles of a sacrificial anode material throughout the protectivecoating have been proposed, once the protective coating is damaged, itcan leave behind an exposed layer that begins to corrode, with thecorrosion working its way under the undamaged coating. Further, noreadily available technique for recharging the protection has beenproposed.

Some embodiments of the present invention feature a method of inhibitingcorrosion of a substrate. The method involves coupling an ionictransport material to the substrate and establishing an electricalconnection between the substrate and a replaceable sacrificial anode.

Some embodiments of the present invention feature a system forinhibiting corrosion of a substrate. The system includes a replaceablesacrificial anode that is disposed relative to the substrate and anionic transport material that is coupled to the substrate. The ionictransport material can be inserted between the substrate and thereplaceable sacrificial anode.

Some embodiments feature a method of inhibiting corrosion of asubstrate. The method involves establishing an electrical connectionbetween the substrate and a replaceable sacrificial anode and couplingan ionic transport material to the substrate. The ionic transportmaterial can establish an ionic connection between the substrate and thereplaceable sacrificial anode.

Certain embodiments feature a system for inhibiting corrosion of asubstrate. The system includes a replaceable sacrificial anode that iselectrically connected to the substrate and an ionic transport materialthat is disposed relative to the substrate and is configured toestablish an ionic connection between the substrate and the replaceablesacrificial anode.

In other examples, any of the aspects above, or any apparatus or methoddescribed herein, can include one or more of the following features.

In some embodiments, the ionic transport material can be coupled to thesubstrate by adhering a continuous layer of the ionic transport materialto the substrate. In certain embodiments, the ionic transport materialis coupled to the substrate by applying the ionic transport material asa top-coat layer to the substrate.

In certain embodiments, the electrical connection between the substrateand the replaceable sacrificial anode can be established by placing thereplaceable sacrificial anode and the substrate in direct physicalcontact. In some embodiments, the electrical connection between thesubstrate and the replaceable sacrificial anode can be established usingan electrical wire. In some embodiments, the electrical connectionbetween the substrate and the replaceable sacrificial anode can beestablished using an electrical conductor included in the ionictransport material. In some embodiments, the ionic transport materialcan include multiple layers. Each layer of ionic transport material canhave an electrical conductivity that is independent of the other layers.

In some embodiments, the ionic transport can be arranged to mechanicallysupport the replaceable sacrificial anode. In certain embodiments, theionic transport material can include a nanoporous solid that supportsionic transfer between the substrate and the replaceable sacrificialanode.

In some embodiments, the replaceable sacrificial anode can include atleast one element less noble than the substrate. In certain embodiments,depletion of the replaceable sacrificial anode can be monitored and inthe event the depletion exceeds a predetermined threshold, an indicationcan be issued to request replacement of the replaceable sacrificialanode.

Other aspects and advantages of the invention can become apparent fromthe following drawings and description, all of which illustrate theprinciples of the invention, by way of example only.

BRIEF DESCRIPTION OF THE DRAWINGS

The advantages of the invention described above, together with furtheradvantages, may be better understood by referring to the followingdescription taken in conjunction with the accompanying drawings. Thedrawings are not necessarily to scale, emphasis instead generally beingplaced upon illustrating the principles of the invention.

FIG. 1A is a block diagram of a system for inhibiting corrosionaccording to some illustrative embodiments of the invention.

FIG. 1B is a block diagram of a system for inhibiting corrosionaccording to certain illustrative embodiments of the invention.

FIG. 1C is a block diagram of a system for inhibiting corrosionaccording to some illustrative embodiments of the invention.

FIG. 2 is a schematic of a system for inhibiting corrosion of asubstrate according to an illustrative embodiment of the presentinvention.

FIG. 3 is a flow diagram of procedures for inhibiting corrosion of asubstrate according to embodiments of the present invention.

DETAILED DESCRIPTION

Some embodiments disclosed herein address the problem of corrosion ofsubstrates (e.g., parts, structures, surfaces, equipment and airframes)through coupling an ionically conductive transport layer to thesubstrate and establishment of an electrical connection between areplaceable sacrificial anode and the substrate to be protected. Theionically conductive layer creates an electrochemical connection betweenthe replaceable sacrificial anode and the substrate by allowing ions toflow between the replaceable sacrificial anode and the substrate. Thereplaceable sacrificial anode includes at least one element that is lessstable than the substrate and, as such, when exposed to environmentalconditions, is oxidized more readily than the protected substrate.During oxidation, electrons travel from the replaceable sacrificialanode to the surface to be protected, resulting in a reduction reaction,thereby preventing oxidation and corrosion of the surface.

By using a replaceable sacrificial anode, embodiments disclosed hereinoffer rechargeable protection of the substrates through replacement ofthe replaceable sacrificial anode. The protection offered by theembodiments disclosed herein is versatile in that it can be applied tovarious surfaces and environmental conditions by adjusting thereplaceable sacrificial anode size, adjusting the spacing betweenmultiple replaceable sacrificial anodes, and adjusting the thickness ofthe ionically conductive layer.

In some embodiments, the ionic conductive transport layer can include ametal organic framework (MOF) and/or polymer layer. The uniformnanoporous MOF can trap water and assist in solvation of the metal ions,thereby promoting ionic transport. Further, in some embodiments, thepolymer can act as a binding agent that provides mechanical support andmaintains the dimensional stability of the ionic transport layer. Incertain embodiments, the ionic transport layer can be used tomechanically connect the replaceable sacrificial anode.

FIG. 1A, FIG. 1B, and FIG. 1C are block diagrams of some embodiments ofthe invention that can be used for inhibiting corrosion of a substrate110. The substrate 110 can be any parts, structures, surfaces,equipment, and airframes that need to be protected against corrosion.The substrate 110 is coupled with an ionic transport material 120. Theionic transport material 120 can be applied over existing paints thatmay have been previously applied to the substrate 110 and/or be designedto replace the existing paints.

In some embodiments, the ionic transport material 120 can be applied asa top-coat layer to the substrate 110. The ionic transport material 120can include a nanoporous solid (e.g., MOF, molecular sieves,mesostructured glass, zeolites, etc.) that can trap water and ensureionic conduction in presence of little to no moisture in the atmosphere.

A replaceable sacrificial anode 130 can be disposed relative to thesubstrate 110. Although a single replaceable sacrificial anode 130 isshown, depending on the application at hand, multiple replaceablesacrificial anodes 130 can be utilized. In some embodiments, a physicalconnection between the replaceable sacrificial anode 130 and thesubstrate 110 can be established using an external clamping mechanism(not shown). As shown in FIG. 1B, in certain embodiments, the physicalconnection between the replaceable sacrificial anode 130 and thesubstrate 110 can be established using the ionic transport layer 120.Connecting the replaceable sacrificial anode 130 to the substrate 110using the ionic transport layer 120 is feasible since it simplifiessystem design by reducing the number of required parts.

An electrical connection between the replaceable sacrificial anode 130and the substrate 110 can be established in a number of ways. Forexample, as shown in FIG. 1B, in some embodiments, the substrate 110 andthe replaceable sacrificial anode 130 can be arranged such that they arein direct physical contact with each other. The physical contactestablished between the two mediums 110, 130 allows for transferringelectrons through the physical contact point, resulting in establishingan electrical connection between the substrate 110 and the replaceablesacrificial anode 130.

In some embodiments, the electrical connection between the substrate 110and the replaceable sacrificial anode 130 can be established byconnecting the two mediums using an electrical wire 140 and appropriateconnectors (not shown). In the embodiments that employ electrical wiresto connect the substrate 110 and the replaceable sacrificial anode 130,further protection can be offered by monitoring the current that flowsduring oxidation of anode along this connection. In some embodiments,the data obtained from monitoring the current flowing between thesubstrate 110 and the replaceable sacrificial anode 130 can be used toprovide a service alert to a user indicating when the replaceablesacrificial anode 130 should be replaced. A change in the potentialdifference between the sacrificial anode and substrate can signalsignificant loss of the sacrificial anode and, therefore, a need toreplace the anode. In some embodiments, when operating in presence ofstable electrical resistance, a change in the current flow can signal areduction in the amount of sacrificial anode and a need to replace theanode. The amount of potential flow/change and/or current flow/changethat is used to indicate the need for replacing the sacrificial anodecan be a function of the system design and/or the application at hand.

In certain embodiments, the electrical connection between the substrate110 and the sacrificial anode 130 can be established through the ionictransport layer 120. For example, as shown in FIG. 1C, the electricalconnection between the substrate 110 and the replaceable sacrificialanode 130 can be established by inclusion of a conductor 150 in theionic transport layer 120. In such embodiments, no additional wires arenecessary. In some embodiments, the conductor 150 can be added under thereplaceable sacrificial anode 130 or into the ionic transport layer 120.In some embodiments, the conductor 150 can be added throughout the ionictransport layer 120. By including the conductor 150 throughout the ionictransport layer 120, the area of electrical connection to the substrate110 can be significantly increased. This increased surface area reducesthe required electrical conductivity of the composite conductor 150 andionic transport layer 120.

In some embodiments, the ionic transport layer 120 can include multiplelayers, each having an electrical conductivity or conductivityproperties that can be different from the electrical conductivity orconductivity properties of other layers. For example, in one embodiment,two layers with distinctly different electrical conductivity orconductivity properties can be used. In some embodiments, the electricalconductivity of a layer (e.g., the top layer) can be maximized byaddition of more conductors 150. In some embodiments, the conductor 150can be selected to maximize the conductivity of the layer along thesurface of the layer, as compared to perpendicular to the surface of thelayer. Further, in some embodiments, the electrical conductivity of alayer (e.g., the bottom layer) can be reduced relative to the otherlayers. In some embodiments, having multiple layers with varyingconductivity levels, can serve to transfer the electrical charge indirections that may be desired/required. For example, when using amulti-layer ionic transport layer 120 that includes a top layer withincreased conductivity (as compared to the other layers) and a bottomlayer with decreased conductivity (as compared to the other layers), aelectrical charge is first distributed across the surface of theconductor 150 and/or the ionic transport layer 120 and then more evenlydown through the coating to the substrate.

FIG. 2 is a schematic of a system for inhibiting corrosion of asubstrate according to an illustrative embodiment of the presentinvention. In the embodiment illustrated in FIG. 2, a replaceablesacrificial anode 230 is directly connected to the ionic transport layer220 and the substrate 210 to be protected, although, as notedpreviously, an electrical connection between the replaceable sacrificialanode 230 and the substrate 210 can be established in a number of ways(e.g., disposing the replaceable sacrificial anode 230 relative to thesubstrate 210 and running an electrical wire between the replaceablesacrificial anode 230 and the substrate 210, placing the replaceablesacrificial anode on top of the ionic transport layer 220 and includinga conductor in the ionic transport layer 220 to ensure electricalconnection, etc.).

As shown in FIG. 2, the cathodic action of the substrate 210 functionsto reduce and extract oxygen (O₂) from the atmospheric air and form ions(OH⁻) that in absence of the ionic transport layer 220 and thereplaceable sacrificial anode can potentially cause corrosion of thesubstrate 210. The ions (OH⁻) are drawn along the conductive pathwaycreated by the greater anodic potential of the replaceable sacrificialanode 230 and through the ionic transport layer 220 to the replaceablesacrificial anode 230 resulting in corrosion of the replaceablesacrificial anode 230. The corrosion of the replaceable sacrificialanode 230 completes the electrochemical circuit created by the substrate210, ionic transport layer 220, and the replaceable sacrificial anode230, inhibiting corrosion of the substrate 210.

The ionic transport layer 220 can be applied to the substrate 210 as astandalone film layer. In some embodiments, the ionic transport layer220 can have a resistivity of less than or about 20000 Ω-cm. In someembodiments, depending on the application at hand and the required levelof protection, the thickness of the ionic transport layer 220 can betailored to attain diverse levels of ion conductance. In someembodiments, the thicknesses of the ionic transport layer 220 can be inthe range of 10 to 100 microns. In addition to the thickness of thecorrosion medium, the corrosion protection offered by the ionictransport layer 220 can depend on the distance of the ionic transportlayer 220 from the sacrificial anode 230 and size of any defects thatmay be present in the ionic transport layer 220.

In some embodiments, in the event multiple replaceable sacrificialanodes 230 are used, having lower values of resistivity for the ionictransport layer 220 can allow for larger spacing between the multiplereplaceable sacrificial anodes 230. The spacing between the replaceablesacrificial anodes 230 can be adjusted to provide efficient corrosionprotection and can be varied to the desired level. In some embodiments,the spacing between the replaceable sacrificial anodes 230 can depend ona number of factors including the thickness of the ionic transport layer220, the conductivity of the ionic transport layer 220, and thecorrosion environment. For example, in one embodiment, when using a15-20 micron thick ionic transport layer 220, the ionic transport layer220 and replaceable sacrificial anode 230 can offer effective corrosionprotection up to about between 2-3 inches from the replaceablesacrificial anode 230. In another embodiment, when using multiplereplaceable sacrificial anode 230 and an ionic transport layer 220having a thickness of about or more than 25 micron, greater ionictransport layer 220 effective protection can be achieved by placing thereplaceable sacrificial anode 230 at 6 inch intervals of one another.The distance between the replaceable sacrificial anodes 230 can beincreased by using a thicker ionic transport layer 220.

The ionic transport layer 220 and replaceable sacrificial anode 230 canfurther provide the substrate 210 with protection even in the presenceof environmental damage, defect, or discontinuities 240 in the ionictransport layer 220. Specifically, depending on the thickness of theionic transport layer 220, the corrosion protection offered by thereplaceable sacrificial anode 230 and ionic transport layer 220 canextend into the damaged and/or scratched areas 240 of the ionictransport layer 220. For example, in one embodiment, two millimeter widedefects in the ionic transport layer can be protected with a 60 micronthick ionic transport layer and with the potential to protect largerdefects at this thickness. In some embodiments, the extent of theprotection offered in a scratch 240 can be proportional to the thicknessof the ionic transport layer 220.

In some embodiments, the ionic transport layer can be directly appliedto the substrate surface to be protected. Depending on application andother factors such as the desired thickness of the ionic transportlayer, various application techniques can be used. For example, theionic transport layer can be applied by spraying, painting, or rollingthe ionic transport layer to the substrate.

In some embodiments, the ionic transport layer 220 can be formed bymixing together a nanoporous MOF and a polymer. The polymer can bepolyacrylonitrile, polyimide, polyvinylidene fluoride, polyurethane, orother similar film forming polymers that effective at binding togetherparticulates. In some embodiments, the ionic transport layer 220 can bedeveloped by mixing of the MOF and one or more polymer solution to forma slurry. Since the ionic transport layer 220 is mechanically supportedby the substrate, the ratio of the polymer to the nanoporous solid canbe adjusted. For applications where the film is self-supporting and/orsupport roll-to-roll processing, additional polymer amounts can be usedto allow for less adjustment in the nanoporous solid content.Adjustments in the ratio of the nanoporous solid content of the ionictransport layer 220 can impact the ionic conduction capabilities of thetransport layer, causing the ionic transport layer 220 to be more (orless) conductive. The change in the conductivity level of the ionictransport layer 220, in turn, can impact the thickness of the ionictransport layer 220 that may be required for a certain applicationand/or effect the sacrificial anode spacing distances that may berequired for that application.

In some embodiments, once the slurry is formed, it is applied to thesubstrate 210 and allowed time to dry. In certain embodiments, thereplaceable sacrificial anode can be directly adhered during theapplication of the slurry or by pressing the replaceable sacrificialanode into the undried/wet ionic transport layer slurry. If applied to awet ionic transport layer slurry, the replaceable sacrificial anode isadhered to the substrate 210 by the dried ionic transport layer 220.

In one embodiment, an ionic transport layer can be used to protect astainless steel substrate. The ionic transport layer can be placed(e.g., coated on as a topcoat) over a surface of a substrate (e.g.,steel) in the form of a film and wetted to increase contact. Areplaceable sacrificial anode (e.g., made of magnesium or zinc) iselectrically connected to the substrate. Upon exposure of the substratesurface to a salt water (NaCl) solution, a potential difference betweenthe surfaces confirms the electrical and ionic connection isestablished. Although corrosion in the substrate can occur in thesurfaces that have not been coated with the ionic transport layer, thesurface under the ionic transport layer is protected from corrosion dueto the ionic and electrical connection established between the substrateand the replaceable sacrificial anode. Further, corrosion inhibition canbe observed in the areas adjacent to the surface coated with ionictransport layer since, due to the anodic potential of the sacrificialanode, ions from such areas can be drawn to the sacrificial anode alongthe ionic transport layer. In some embodiments, protection tounprotected areas can extend to about 2 millimeter beyond the areascovered with the ionic transport layer.

In one embodiment, in order to evaluate and compare the effectiveness ofthe ionic transport layer in providing a substrate protection againstcorrosion, a solution including synthetic sea water can be used. Thesynthetic sea water can be formed by adding approximately 50 grams ofsodium chloride (NaCI), 22 grams of magnesium chloride (MgCl,2.6H20),3.2 grams of calcium chloride (CaCh,2H20), and 8.0 grams of sodiumsulfate (Na2S04) to approximately one liter of distilled water. Themultiple substrate surfaces can be observed, of which some are leftunprotected, some have been protected with urethane, some have beencoated with a layer of the ionic transport layer, and some have beencoated with both a layer of the ionic transport layer and a layer ofurethane. The application of the urethane after the ionic transportlayer provides additional abrasion resistance without inhibiting ionflow.

A spray test solution can be prepared by adding approximately 2milliliter of sulfurous acid (6.4 percent assay as SO2) to each liter ofthe synthetic sea water. The spray test solution can have a PH that ismaintained approximately between 3.3 and 3.5. The substrate can betested by mounting the substrate on a motor and spinning it around whilespraying the substrate surfaces. The substrate can be tested for anumber of hours (e.g., multiple hour long tests, conducted a few (e.g.,four) hours apart from one another). Once the testing is completed, thesubstrate surface can be observed using an optical microscope todetermine the extent of corrosion.

Upon conducting such experiment, corrosion in uncoated surfaces can beobserved rapidly. In the surfaces coated with urethane, due to thehydrophobic nature of urethane, corrosion is not observed even after atwo hour long spray session. However, once scratched to expeditecorrosion, corrosion in the surface initiates after about an hour andbecomes more significant about after two hours into a spray session, andeven continues to expand on storage. In contrast, substrate surfacesprotected by the ionic transport layer, even when scratched, demonstrateno corrosion during or after corrosion testing.

FIG. 3 is a flow diagram of procedures for inhibiting corrosion of asubstrate according to embodiments of the present invention. An ionictransport layer can be coupled with a substrate surface (block 310). Theionic transport layer can be coupled with the substrate in a number ofways, for example by painting, rolling, etc. a layer of the ionictransport layer onto the substrate.

Further, a replaceable sacrificial anode can be disposed adjacent to thesubstrate (block 320). The replaceable sacrificial anode includes atleast one element that is less stable than the substrate and, as such,when exposed to environmental conditions, is oxidized more readily thanthe protected substrate. In some embodiments, more than one replaceableanode can be used. The replaceable sacrificial anode can be coupled tothe substrate in a number of ways (e.g., using an external clampingmechanism or through the ionic transport layer).

Corrosion in the substrate can be inhibited by establishing anelectrical and ionic connection between the replaceable anode and thesubstrate (block 330). An electrical connection between the replaceablesacrificial anode and the substrate can be established in a number ofways (e.g., using an electrical wire, bringing the substrate and thesacrificial anode in direct contact, by including a conductor in theionic transport layer).

The electrical connection (e.g., current flow) between the substrate andthe sacrificial anode can be monitored (block 340) to determine whetherthe anode has depleted. If the anode has depleted beyond a certainthreshold, a user can be alarmed to replace the sacrificial anode (block320).

While the invention has been particularly shown and described withreference to specific illustrative embodiments, it should be understoodthat various changes in form and detail may be made without departingfrom the spirit and scope of the invention.

What is claimed is:
 1. A method of inhibiting corrosion of a substrate,the method comprising: coupling an ionic transport material to thesubstrate; and establishing an electrical connection between thesubstrate and a replaceable sacrificial anode.
 2. The method of claim 1wherein coupling the ionic transport material to the substrate includesadhering a continuous layer of the ionic transport material to thesubstrate.
 3. The method of claim 1 wherein coupling the ionic transportmaterial to the substrate includes applying the ionic transport materialas a top-coat layer to the substrate.
 4. The method of claim 1 furtherincluding establishing the electrical connection between the substrateand the replaceable sacrificial anode by placing the replaceablesacrificial anode and the substrate in direct physical contact.
 5. Themethod of claim 1 further including establishing the electricalconnection by providing an electrical link between the substrate and thereplaceable sacrificial anode using an electrical wire.
 6. The method ofclaim 1 further including coupling the replaceable sacrificial anode tothe ionic transport material and establishing the electrical connectionbetween the substrate and the replaceable sacrificial anode using anelectrical conductor included in the ionic transport material.
 7. Themethod of claim 6 further including a multi-layer ionic transportmaterial, each layer of the ionic transport material having anelectrical conductivity independent of other layers.
 8. The method ofclaim 1 further including mechanically supporting the replaceablesacrificial anode using the ionic transport material.
 9. The method ofclaim 8 further including monitoring depletion of the replaceablesacrificial anode and in an event the depletion exceeds a predeterminedthreshold, issuing an indication requesting replacement of thereplaceable sacrificial anode.
 10. The method of claim 1 wherein thereplaceable sacrificial anode includes at least one element less noblethan the substrate.
 11. The method of claim 1 wherein the ionictransport material includes a nanoporous solid, the nanoporous solidssupporting ionic transfer between the substrate and the replaceablesacrificial anode.
 12. A system for inhibiting corrosion of a substrate,the system comprising: a replaceable sacrificial anode disposed relativeto the substrate; and an ionic transport material coupled to thesubstrate, the ionic transport material being inserted between thesubstrate and the replaceable sacrificial anode.
 13. The system of claim12 wherein the ionic transport material is coupled to the substrate byadhering a continuous layer of the ionic transport material to thesubstrate.
 14. The system of claim 12 wherein the ionic transportmaterial is coupled to the substrate by applying the ionic transportmaterial as a top-coat layer to the substrate.
 15. The system of claim12 wherein electrical connection between the substrate and thereplaceable sacrificial anode is established by placing the replaceablesacrificial anode and the substrate in direct physical contact.
 16. Thesystem of claim 12 wherein electrical connection between the substrateand the replaceable sacrificial anode is established using an electricalwire.
 17. The system of claim 12 wherein the ionic transport is arrangedto mechanically support the replaceable sacrificial anode.
 18. Thesystem of claim 17 wherein electrical connection between the substrateand the replaceable sacrificial anode is established using an electricalconductor included in the ionic transport material.
 19. The system ofclaim 18 wherein the ionic transport material includes multiple layers,each layer of the ionic transport material arranged to have anelectrical conductivity independent of other layers.
 20. The system ofclaim 12 further including a monitor arranged to monitor depletion ofthe replaceable sacrificial anode and in an event the depletion exceedsa predetermined threshold, issue an indication requesting replacement ofthe replaceable sacrificial anode.
 21. The system of claim 12 whereinthe replaceable sacrificial anode includes at least one element lessnoble than the substrate.
 22. The system of claim 12 wherein the ionictransport material includes a nanoporous solid that supports ionictransfer between the substrate and the replaceable sacrificial anode.23. A method of inhibiting corrosion of a substrate, the methodcomprising: establishing an electrical connection between the substrateand a replaceable sacrificial anode; and coupling an ionic transportmaterial to the substrate, the ionic transport material establishing anionic connection between the substrate and the replaceable sacrificialanode.
 24. The method of claim 23 further including establishing theelectrical connection between the substrate and the replaceablesacrificial anode by at least one of placing the replaceable sacrificialanode and the substrate in direct physical contact, connecting thereplaceable sacrificial anode and the substrate in using an electricalwire, or using an electrical conductor included in the ionic transportmaterial.
 25. A system for inhibiting corrosion of a substrate, thesystem comprising: a replaceable sacrificial anode being electricallyconnected to the substrate; and an ionic transport material disposedrelative to the substrate and configured to establish an ionicconnection between the substrate and the replaceable sacrificial anode.26. The system of claim 25 wherein electrical wherein electricalconnection between the substrate and the replaceable sacrificial anodeis established through at least one of direct physical contact betweenthe replaceable sacrificial anode and the substrate, an electrical wireconfigured to connect the replaceable sacrificial anode and thesubstrate, or an electrical conductor included in the ionic transportmaterial.